Warren Richey of The Christian Science Monitor reported that the Mexican government submitted a 45-page friend-of-the-court brief in support of the Obama administration to the court. Sixteen countries joined the Mexico brief, including El Salvador, Guatemala and Honduras. The brief claims that the Arizona law will undermine foreign relations between the US federal government and other governments. Since SB 1070 was passed, the Mexican government has issued a travel warning, calling Arizona an adverse political atmosphere. Richey also recounts what the brief does not say — that Mexico, El Salvador, Guatemala and Honduras contribute 73 percent of all illegal immigrants in the US.

The most controversial provision in the Arizona law requires police officers to verify the immigration status of people they suspect are in the country illegally, according to Jeremy B. White of the International Business Times. The Obama administration argues that the provision deputizes local and state law enforcement to perform a task reserved for federal immigration officers. If each state sets its own immigration policy, the administration argues, it would subvert Congress’s goal of maintaining a single national approach. The administration recently passed guidelines asking officers to prioritize the apprehension of criminal aliens, which could become untenable if Arizona’s law is upheld.

The Arizona case is similar to the health-care case heard a few weeks ago, insofar as it will define the boundaries between state and federal jurisdiction, according to Greg Stohr of Bloomberg News. The lawyers on both sides of the case argued against each other before in the health care case. US Solicitor General Donald Verrilli, arguing in favor of the Obama administration, claims that the federal government has the ultimate authority to regulate immigration. Paul Clement, a Washington lawyer who is defending Arizona, is arguing that Arizona police offers have an inherent authority to enforce the immigration laws.

Bill Mears, a CNN Supreme Court Producer, reports that the legal issue before the courts is whether states have the authority to enforce immigration matters, or whether this role is within the exclusive authority of the federal government. Lower level federal courts have already blocked four parts of SB 1070. As the court began hearing the arguments, a report was released claiming that Mexican immigration to the US has come to a standstill.

UPI reported that Sen. Charles Schumer (D-NY) would introduce a bill that would stop states from enacting their own immigration enforcement laws, should the court uphold the Arizona laws. Schumer remarked that state activism in immigration would be too damaging to the economy and too dangerous for democracy. Sen. John Cornyn (R-TX) called Schumer’s hearing “election-year theater.”